Tranexamic acid (trans-4-(aminomethyl)cyclohexanecarboxylic acid, Cyklokapron® (Pfizer) is an antifibrinolytic agent. That is, it helps to prevent lysis or dissolution of a fibrin clot which forms in the normal physiologic process of hemostasis. Its mechanism of action is as a competitive inhibitor of plasminogen activation, and as a noncompetitive inhibitor of plasmin; both plasminogen and plasmin are activators of fibrinolysis and active clot-lysing agents. Tranexamic acid thus helps to stabilize fibrin clots, which in turn maintains coagulation and helps to control bleeding.
Tranexamic acid is used to control excess bleeding, for example, excess bleeding that occurs during dental procedures in hemophiliacs and for heavy bleeding during menstruation (menorrhagia). Women suffering from menorrhagia are typically treated orally with 500 mg tranexamic acid tablets administered three or four times daily with a total daily dose ranging from 3 grams/day (two tablets every eight hours) to 6 grams/day (three tablets every six hours). However, this treatment may cause adverse gastrointestinal reactions, including nausea, vomiting, diarrhea, and cramping, etc. These gastrointestinal side effects are due to the quantity of tranexamic acid and/or rapid rate of release of tranexamic acid into the stomach with each dose, as well as the large quantity of excipients used in the tablet formulation that are introduced into the stomach. Such side effects, in addition to the cramping, bloating, pain, and other symptoms that may accompany menses, are undesirable, and a formulation of tranexamic acid is needed which will reduce or eliminate these side effects.
Menstrual Bleeding
Menstrual Bleeding disorders encompass a number of conditions including bleeding associated with uterine fibroids, endometriosis, or bleeding as a result of deficiencies in the clotting process for example, von-Willebrand's disease. Studies suggest that as many as 11% of the women who experience heavy menstrual bleeding, suffer from an inherited bleeding disorder such as von Willebrand's disease. Excessive Menstrual Bleeding is menstruation at relatively regular intervals but with excessive blood loss over the menses period which may be prolonged. Heavy Menstrual Bleeding (also referred to as “Menorrhagia”) is a serious, persistent, and recurrent medical condition that is one of the most common complaints encountered by gynecologists and primary care physicians (Palep-Singh, 2007). A 2005 survey of 273 obstetrician/gynecologists found that they see an average of 18 to 25 symptomatic patients per month. Heavy Menstrual Bleeding is a hyperfibrinolytic condition defined as cyclic, normal intervals of menstruation with excessive volume. Menorrhagia is often associated with a disruption in daily routines, work, and sexual activity leading to a significant decrease in health-related quality of life and time lost from work or school. While Menorrhagia is rarely life threatening, when undiagnosed and untreated, it may over time cause iron deficiency anemia and increased fatigue, both of which affect normal life activities, relationships, social activities, and various aspects of mental well-being (irritation, anxiety). Left untreated it may be associated with subsequent morbidity including dysmenorrhea, hospitalization, red blood cell transfusions and chronic pain. Annually, approximately 10% of women of reproductive age report Menorrhagia (Rees 1991; van Eijkeren, 1992) and according to the Center for Disease Control (CDC), 3 million women of reproductive age report Menorrhagia yearly, 60% of which have no known etiology. Studies report that as many as thirty percent of premenopausal women perceive their menses to be excessive.
Women suffering from menorrhagia often have greater uterine fibrinolytic activity than women with normal cyclic menstrual blood loss (MBL). High concentrations of plasminogen activators are found in both the uterus and menstrual fluid (Albrechtsen, 1956a,b). Rybo (1966) found significantly higher concentration of endometrial plasminogen activators in women with excessive menstrual bleeding compared to women with normal menstrual loss.
Causes of Menorrhagia include pelvic diseases (myomata [fibroids], adenomyosis or uterine polyps), intrauterine contraceptive devices, and systemic disorders (coagulopathies such as thrombocytopenia or von Willebrand's disease, and hypothyroidism). In contrast to menorrhagia, the term ‘dysfunctional uterine bleeding’ refers to excessive, prolonged or irregular bleeding from the endometrium that is unrelated to systemic disease (Wathen, 1995), and is usually associated with anovulation. Menorrhagia is also distinguished from other ovulatory bleeding disorders, such as metrorrhagia (intermenstrual bleeding), menometrorrhagia (irregular heavy menstrual bleeding) and polymenorrhea (menstrual cycle less than 21 days).
Diagnosis of Menstrual Blood Loss
In clinical trials, menstrual blood loss (MBL) is usually determined by measuring the amount of hemoglobin recovered from sanitary products during the menstrual cycle, using the alkaline hematin method (Fraser, 1994). However, it is important to remember that blood accounts for only about 50% of total menstrual flow, with endometrial transudate accounting for the remainder (Fraser, 1994). Total menstrual flow can be estimated by weighing of sanitary products or by comparisons with a pictorial blood loss assessment chart. However, the use of these quantitative and semi-quantitative methods is not practical in non-trial settings. Rather, the diagnosis of Menorrhagia in the healthcare clinic is made by medical providers on the basis of patient's perceived and self-reported medical history, routine laboratory assessments of the patient's general health status, and gynecological examinations.
Clinically heavy menstrual bleeding is sometimes defined as total blood loss exceeding about 80 ml per cycle or menses lasting longer than seven days. The volume lost however, varies widely. Clinically losses from about 30 ml to 60 ml, 60 to 80 ml, 80 to 100 ml, to as high as 1000 ml per cycle are observed. Menstrual blood losses of 50 to 60 ml are associated with a negative iron balance and iron deficiency anemia is diagnosed in about 67% of the women who lose an excess of 80 ml per day. Other criteria for diagnosing the condition include measuring the number and size of blood clots in the meneges, or monitoring the use of pads or tampons. It is estimated that perhaps only ten percent of women who perceive their loss to be excessive actually fall within the clinical definition. The 80 ml definition has been repeatedly questioned, and alternative definitions broadened the blood loss range used for patient evaluations.
Blood loss volume assessments commonly require the collection and preservation of menstrual pads or tampons, the extraction of the pads and the accurate measurement of the blood content. Women are instructed to collect all sanitary towels and tampons during the course of the menstrual diagnosis period or the course of a clinical study period. Blood loss can be measured by extraction of the blood from the sanitary material with 5% sodium hydroxide followed with a spectrophotometric measurement of hematin at a wavelength of about 540 nm. The total blood loss can be calculated for an individual by comparison of the patients plasma blood hemoglobin measurement with the collected hemoglobin values.
The collection of the blood sample discourages the routine use of the test in the diagnosis or in the treatment of the condition. In the course of a routine visit with a physician other blood work may be appropriate but lacks a casual relation to the heavy bleeding disorder. The battery of routine laboratory tests may include patient blood hemoglobin, haematocrit, platelet count, bilirubin, serum creatinine and serum ferritin. In sum, diagnosis in the routine course of practice relies heavily on the woman's perception of the volume of blood lost during menses.
Diagnosis and Treatment of Heavy Menstrual Bleeding Disorders (Menorrhagia)
A number of medical and surgical interventions are available to treat menstrual bleeding disorders. Currently available non-surgical treatments for heavy bleeding disorders, include, hormonal treatments (e.g., oral contraceptives), high-dose progestin therapy, desmopressin acetate, ethamsylate, nonsteroidal anti-inflammatory drugs (NSAIDs), the antifibrinolytic drugs aminocaproic acid and tranexamic acid. Even with the drug treatments available, surgery remains a common treatment.
Although not approved for menorrhagia in the US, use of oral contraceptives for menorrhagia is widely accepted. Oral contraceptives may not be a preferred therapy for some women because of age (younger females), unwanted side effects (nausea and vomiting, breakthrough bleeding, weight change, migraines and depression), and safety concerns (increased risk of thromboembolism, stroke, myocardial infarction, hepatic neoplasia and gall bladder disease). High-dose progestin (synthetic versions of the hormone progesterone) may also be given to women with menorrhagia, either orally or by a progestin-releasing device inserted into the uterus (intrauterine device). Side effects include nausea, bloating, mood changes, and breast tenderness.
Although it is typically a last resort, desmopressin acetate is sometimes used to help lighten menstrual flow in women with menorrhagia. The effectiveness of desmopressin is thought to vary between individuals. Side effects include headache, tachycardia, facial flushing, and rare reports of thromboembolism.
NSAIDs are sometimes used to treat menorrhagia as they may reduce blood flow while providing analgesia for pain associated with the condition (Shaw, 1994). Side effects associated with chronic NSAID use include gastrointestinal bleeding, ulceration, and perforation; and renal effects such as hyperkalemia, hyponatremia, acute renal insufficiency, interstitial nephritis, and renal papillary necrosis.
Hysterectomy or endometrial resection are options if other forms of therapy are not effective or are unsuitable for some reason. Possible surgical complications include infection, uterine perforation, and other complications associated with major surgery.
Antifibrinolytic drugs, such as ε-aminocaproic acid and tranexamic acid (immediate-release formulation) have been used to treat HMB in women with or without a diagnosed bleeding disorder (van Eijkeren, 1992; Bonnar, 1996; Vermylen, 1968; Nilsson, 1965). The available evidence from published literature suggests that tranexamic acid at doses of ˜4 g/day (typically 1 g every 6 hours) is effective in the treatment of HMB and is associated with few side effects (Callender, 1970; Dunn, 1999; Edlund, 1995; Preston, 1995). In Sweden, the average dose of tranexamic acid to treat HMB is 3.9 g/day (Rybo, 1991). Thus, tranexamic acid is used extensively in Europe, Canada, Asia, Japan, Australia and New Zealand to treat menorrhagia, but is not approved for this indication in the US.
Tranexamic acid is a competitive inhibitor of plasminogen activation (see review by Dunn, 1999). Binding of tranexamic acid to plasminogen does not prevent conversion of plasminogen to plasmin by tissue plasminogen activator, but the resulting plasmin/tranexamic acid complex is unable to bind to fibrin. Thus, enzymatic breakdown of fibrin by plasmin (fibrinolysis) is inhibited. At higher concentrations, tranexamic acid is also a noncompetitive inhibitor of plasmin.
Before medical and surgical interventions can be initiated, diagnosis of a heavy menstrual bleeding disorder must be accomplished.
Diagnosis and treatment of disease often depends on the patient's perception and subsequent description of symptoms, the physician's evaluation of the patient's description, the physician observations of the patient and laboratory test results. Menstrual bleeding disorders do not lend themselves to physician observation or to routine laboratory testing. Patient observations and the physician's evaluation of the patient's description are subjective and thus variable. In addition a women's medical history has been found to be a poor predictor of menstrual blood loss. Neither the duration of menses nor the number of sanitary pads worn accurately corresponds to the woman's actual menstrual blood loss (Chimbira, Haynes, year). An objective assessment of blood loss using the alkaline haematin assay has been shown to be reproducible but it is not suited for routine clinical use by healthcare providers. To date no effective instrument for reliably diagnosing and/or monitoring the treatment of menstrual bleeding disorders has been developed despite the significant number of women who suffer from these conditions.
Previously, studies have focused on the impact of symptoms of bleeding disorders on patients' health related quality of life. As the effects of menstrual bleeding disorders are primarily symptomatic, the subjective outcome namely symptom alleviation, cannot be objectively measured. In research from European countries where the antifibrinolytic drug tranexamic acid is currently available, treatment with this antifibrinolytic has reduced heavy menstrual bleeding by 40-50% and improved the health-related quality of life of affected women on measures of social activity, work performance, productivity, cleanliness, overall functioning and tiredness.
Jenkinson et al, Quality in Health Care 1996; 5; 9-12 evaluated the validity and internal reliability of the short form-36 (SF36) health survey questionnaire in women presenting with menorrhagia. The study concluded that several questions on the questionnaire were difficult to answer for patients with heavy menstrual bleeding. Such problems were suggested as possible interferences with the validity of the measure. Jenkinson warns that because a subjective measure works well in one population or with one group, this cannot be taken to imply its appropriateness for all groups or conditions.
Edlund, in an abstract from a seminar on Dysfunctional Uterine Bleeding, Feb. 23, 1994, indicates that a questionnaire was used in a Swedish study of 2205 women who described their menstruation as excessive.
Winkler in a study based in part on the Edlund work, concluded that the treatment of heavy menstrual bleeding with tranexamic acid increased the quality of life of the treated patients. The Winkler study was an open label uncontrolled usage study which included 849 patients. A questionnaire was used prior to treatment and after the first and third menstruation. The study indicates that 80% of the women were satisfied with the treatment. The questionnaire used a series of eight question combined with an assessment by the patients of the change in quantity of menstrual flow.
Ruta, D. A., Quality of Life Research, 4, (33-40), 1995 finds that menorrhagia is a common problem in gynecological practice and that women seek professional help primarily because of the deleterious effect on their quality of life. Ruta recognizing the importance of evaluating the effectiveness of the treatments developed a questionnaire based on the type of questions frequently asked when taking a gynecological history. A series of questions were devised which assessed fifteen factors including the duration of the period, the regularity of the period, pain, problems with soiling/staining, interference with work, interference with leisure. Ruta concluded that the clinical questionnaire may be useful in selecting patients for hysterectomy and assessing the outcome of conservative treatment especially in combination with the SF-36 questionnaire.
Diagnostic Test for Menstrual Bleeding
The alkaline haematine test described above provides quantitative assessments of the extent of menstrual bleeding. This test allows the physician to diagnose and monitor the progress of a women's menstrual process. However the test is impractical and difficult to perform. The test requires women to capture used menstrual pads over the course of her period, preserve the samples in a condition such that the blood content within the pad may be accurately extracted and quantitated. Requesting a patient to perform menses sample collection may be practical in the course of a clinical trial where procedures are specified and monitored however, in routine medical practice, the use of such a test procedure to diagnose and monitor a women's menstrual bleeding is impractical and the data generated is unreliable.
The need remains to develop an assessment system which replaces previously studied diagnostic techniques and the alkaline haematine test and provides a reliable measure of both the occurrence of the disorder and the progress of the disorder. The present invention fills this need by providing a Heavy Menstrual Bleeding Instrument (HMBI) which is capable of diagnosing, and monitoring the treatment of a patient with a menstrual bleeding disorder.
There also remains a need to provide Heavy Menstrual Bleeding (HMB) therapy that is safe, efficacious and only administered during the monthly period of heavy menstruation, addresses the excessive fibrinolysis implicated in many causes of menorrhagia, and fills a currently recognized unmet medical need in the US. Therapy for HMB is expected to reduce the incidence and extent of iron-deficiency anemia, and to provide a nonhormonal medical therapy option in lieu of the numerous invasive procedures (e.g., transcervical endometrial resection) and major surgery (hysterectomy) performed annually.